Reference scale

A known-size ruler, target, or calibrated feature placed in the same plane as photographed or measured damage.

Meaning and boundaries

A nearby object, zoom level, or image metadata is not a reliable scale unless geometry and calibration are controlled.

Why it matters in glass restoration

It lets reviewers estimate feature size and compare condition over time without relying on memory.

Related terms

• Condition photograph
• Damage map
• Magnification
• Damage length

References

• U.S. National Park Service — Preservation Matters: Stained Glass
  Publisher’s original source
• National Institute of Standards and Technology — Fractography of Ceramics and Glasses, 3rd edition
  Publisher’s original source
• National Bureau of Standards / NIST — The Science of Ceramic Machining and Surface Finishing II
  Publisher’s original source